feat: add admin dashboard app

- React + Vite + TanStack Router + TanStack Query
- Auth with better-auth (login, session, admin guard)
- Source config management (WeatherKit credentials, user config)
- Feed query panel
- Location push card
- General settings with health check
- CORS middleware for cross-origin auth
- Disable CSRF check in dev mode
- Sonner toasts for mutation feedback

Co-authored-by: Ona <no-reply@ona.com>

apps/admin-dashboard/src/components/ui/separator.tsx

@@ -0,0 +1,26 @@
+import * as React from "react"
+import { Separator as SeparatorPrimitive } from "radix-ui"
+
+import { cn } from "@/lib/utils"
+
+function Separator({
+  className,
+  orientation = "horizontal",
+  decorative = true,
+  ...props
+}: React.ComponentProps<typeof SeparatorPrimitive.Root>) {
+  return (
+    <SeparatorPrimitive.Root
+      data-slot="separator"
+      decorative={decorative}
+      orientation={orientation}
+      className={cn(
+        "shrink-0 bg-border data-horizontal:h-px data-horizontal:w-full data-vertical:w-px data-vertical:self-stretch",
+        className
+      )}
+      {...props}
+    />
+  )
+}
+
+export { Separator }